Improvement of the fuel properties of dairy manure by increasing the biomass-to-water ratio in hydrothermal carbonization

Abstract

There are many advantages to liquid-based hydrothermal carbonization (L-HTC) but the need to immerse the biomass in water generates more post-process water, hindering the commercialisation of HTC. To address this issue, this study investigated the feasibility of vapour-based HTC (V-HTC), which minimizes the water required. Dairy manure was hydrothermally treated at temperatures of 200, 230, 255 and 270°C and biomass-to-water ratios (B/W) of 0.1, 0.18, 0.25, 0.43, 0.67 and 1.0 for 20 minutes, then the produced hydrochars were characterized by calorific, proximate, ultimate and thermogravimetric analyses. The results showed that the mass yields of hydrochar decreased with increasing temperature but were essentially stable at high B/W ratios. Notably, the calorific values of the hydrochars increased with increasing temperature and B/W ratio, and the energy density increased by 46%. Due to the higher mass yield and increased energy density, maximum energy yields at each temperature (86.0–97.4%) were observed at a B/W ratio of 1.0. The proximate and ultimate analyses revealed that the degree of coalification, such as the increase in carbon content and decrease in oxygen and volatile matter, progressed more under V-HTC than L-HTC conditions, likely because the lower liquid content in V-HTC facilitates the formation of secondary char and increases the reaction severity due to higher acidity. This study showed a potential approach for upgrading a semi-solid-state biomass by V-HTC.

Elaeis guineensis leaves for potential renewable sub‐bituminous coal: Optimization of biochar yield by response surface methodology and product characterization

“…The high H/C and the low O/C result in increased HHV of solid fuels because H tends to release more energy when burnt due to its higher energy content per unit mass than C and O 72 . The elemental composition of the OPL biochar shifted closer towards sub‐bituminous coal and possessed a sufficient HHV 73–75 .…”

“…The high H/C and the low O/C result in increased HHV of solid fuels because H tends to release more energy when burnt due to its higher energy content per unit mass than C and O. 72 The elemental composition of the OPL biochar shifted closer towards sub-bituminous coal and possessed a sufficient HHV. [73][74][75] These results further suggest their potential for energy applications, such as steam generation for electricity production in power plants.…”

Recent Advances of Solvent Effects in Biomass Liquefaction Conversion

“…The boiling point of the solvent, which is closely related to its saturated vapor pressure, has a profound impact on the yield of bio-oil. Specifically, an elevated vapor pressure favors the occurrence of secondary reactions, such as thermal cracking, repolymerization, and recondensation, that lead to the formation of a more coalified and stable solid product [49]. However, this high vapor pressure hinders the critical degradation reactions of biopolymers [50,51] and hemicellulose [52], which are the primary sources of bio-oil.…”